The use of wireless networks for mobile communication (e.g., voice and/or data communication) continues to grow at a rapid pace. Part of that growth is a desire for increased network capacity and improved quality of service for users of such wireless networks. Such increased network capacity and improved quality of service may be achieved, at least in part, by increasing available bandwidth of wireless networks. Increases in bandwidth may allow for increased use and/or improved quality of service for network users.
Advancements in wireless network technology are being continually investigated in order to keep pace with increasing use and quality of service expectations. For instance, the Third Generation Partnership Project (3GPP) is currently developing standards for an Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), which is, in part, an evolvement of UMTS. The E-UTRAN standards are also referred to as the Long Term Evolution (LTE) standards or the Evolved UMTS Terrestrial Radio Access (E-UTRA) standards. UMTS, in turn was evolved, in part, from the Global System for Mobile Communications (GSM).
In the following, the term GSM applies to all GSM-based systems such as GSM itself, General Packet Radio Service (GPRS), Enhanced Data rates for Global Evolution (EDGE), and any evolution thereof, the term UMTS applies to all UMTS-based systems such as UMTS itself, High Speed Downlink Packet Access (HSDPA), and any evolution thereof, the term LTE (E-UTRA, E-UTRAN) refers to all LTE-based systems and any evolution thereof.
When new wireless network technologies are introduced (as will be the case with E-UTRAN (LTE)), the new technologies are typically deployed in conjunction with existing technologies, thus creating multi-mode networks (e.g., networks implementing multiple wireless communication standards simultaneously). Such an approach allows for the investment in new technologies to be made over time, as well as allowing for continued use of investments made in previous technologies. Thus, it is foreseeable that multi-mode wireless networks including GSM, UMTS and E-UTRAN coverage will exist.
One consideration that is taken into account when deploying new technologies along with existing technologies in a multi-mode network is the interworking between the new technology and the existing technology, or technologies. Interworking is needed so that wireless network users are able to move between wireless coverage of existing technologies and wireless coverage of new technologies while maintaining continuity of service as far as possible. In such a situation, a mobile device that is being used would be compatible with both the existing technologies, as well as the new technology, e.g., a multi-mode mobile device that is compatible with GSM and LTE.
One aspect of interworking for wireless telecommunication networks is how to handle the process of handing over (handing off) mobile devices from wireless communication cells (e.g., such as defined by a base station) of one technology to communication cells of another technology. Such handoffs may occur when the mobile device is actively communicating in the multi-mode network (e.g., engaged in a voice or data call) or, alternatively, may occur when the mobile device is operating in an idle mode in the multi-mode network (e.g., connected with the network but not actively communicating).
In order to facilitate such hand overs, a mobile device receives information regarding one or more neighboring cells from a base station of its current cell. The mobile device then makes signal measurements (e.g., signal strength measurements) for signals received from the neighboring cells and provides measurement reports including, or based on, the signal measurements to its current base station. Based on the signal measurements and/or the measurement reports, the mobile device may initiate hand over to a neighboring cell (e.g., with better signal quality than its current cell) or the mobile device's current base station may initiate hand over to a neighboring cell. Such signal measurement and handing over may occur when the mobile device is actively communicating or while the mobile device is operating in idle mode (e.g., connected to the network but not communicating via an active communication channel). For the mobile device to report measurements, there must be an active communication channel established, even if only to provide a measurement report.
As is known, mobile devices, e.g., in GSM and UMTS, use a control channel of their current cell's base station to provide measurement reports for the signals. Typically, such control channels have limited bandwidth. A mobile device operating in a multi-mode network makes signal measurements and provides measurements reports for neighboring cells of each technology with which it is compatible. For instance, a tri-mode phone (e.g., compatible with GSM, UMTS and LTE) will make signal measurements and provide measurement reports for neighboring GSM cells, neighboring UMTS cells and neighboring LTE cells if such neighboring cells are indicated by the multi-mode network.
Due to differences in wireless technologies (e.g., differences between existing technologies and new technologies) facilities for executing hand overs in some circumstances may not be available or, alternatively, may be limited. For instance, while GSM and UMTS provide for circuit-switched only connections (e.g., for voice traffic), LTE will be implemented as a packet-switched only network. Therefore, facilities for hand over of GSM and/or UMTS circuit-switched connections (i.e., dedicated mode, radio resource connections) to LTE packet-switched connections in LTE cells may not be available, or may be limited.
In such situations, i.e., where hand over facilities are either not available or are limited, performing signal measurements and measurement reporting for all signals received from neighboring cells to which hand over is not available or limited has some drawbacks. First, performing such signal measurements consumes battery charge for the mobile device performing the measurements. Second, making such measurements reduces the time available to make other signal measurements, such as for cells where hand over is possible or is not limited. Third, providing measurement reports for such signal measurements reduces the already limited bandwidth available in a control channel (e.g., for an associated base station) for reporting the other signal measurements (e.g., for cells where handover is possible or not limited).